(1) Field of the Invention
This invention relates to a device for the collection, phase separation, and serum dispensing, of two-phase liquids such as blood.
(2) State of the Prior Art
Blood collection and phase separation devices have long recognized the necessity for a partition which will maintain phase separation of serum and cells after separation is achieved by centrifugation. Movable mechanical "pistons" were first used for this purpose. Subsequent movable partitions incorporated filters so that the clogging of the filters with fibers and cells of the heavier phase would automatically terminate movement of the pistons at the fluid interface.
To avoid the oft-times elaborate piston constructions of the type noted above, certain researchers turned to the use of thixotropic, inorganic gels for the partition, either alone or in combination with mechanical piston-like members, as disclosed for example in U.S. Pat. No. 3,909,419 issued on Sept. 30, 1975. Because of the specific gravity of the gel and/or the incorporated mechanical pieces, the phase separation interface was automatically reached by the partition.
However, none of the preceding approaches contemplate the incorporation of a dispensing chamber with the collecting and phase separating device.
U.S. Pat. No. 3,977,568 issued Aug. 31, 1976 discloses devices having a dispensing chamber coupled with a blood collection compartment to permit closed flow from one to the other. These devices obviate exposure of the serum to the atmosphere and the operator. The disclosed arrangements require the use of at least one valve disposed between the separating compartment and dispensing chamber, to protect the serum-collecting end of the phase separation compartment from whole blood contamination, and at least one step by an operator is required to actuate the valve.